Salubrinal attenuated retinal neovascularization by inhibiting CHOP-HIF1α-VEGF pathways.

Yaguang Hu,Shanshan Yu,Jingjing Huang,Qiaochu Cheng,Yue Xu,Boyu Yang,Xiaoling Liang,Dan Ye,Xi Lu,Ching-Kit Tsui,Lin Lu

doi:10.18632/oncotarget.20431

Abstract

Retinal neovascularization (RNV) related disease is the leading cause of irreversible blindness in the world. The aim of this study is to identify whether salubrinal could attenuate RNV by inhibiting CCAAT/enhancer-binding protein (C/EBP) homologous protein (CHOP)- hypoxia inducible factors 1α (HIF1α) -vascular endothelial growth factor (VEGF) pathways in both mouse retinal microvascular endothelial cells (mRMECs) and oxygen-induced retinopathy (OIR) mouse model. After being treated with salubrinal (20μmol/L) or CHOP-siRNA, mRMECs were exposed to a hypoxia environment. OIR mice were intraperitoneally injected with salubrinal (0.5 mg/kg/day) from P12 to P17. With salubrinal or CHOP-siRNA treatment, the elevated CHOP protein and mRNA levels in hypoxia-induced mRMECs were significantly decreased. HIF1α-VEGF pathways were activated under hypoxia condition, then HIF1α protein was degraded and VEGF secretion was down-regulated after salubrinal or CHOP-siRNA treatment. In OIR mice, the areas of RNV were markedly decreased with salubrinal treatment. Moreover, elevated expressions of CHOP, HIF1α and VEGF in retinas of OIR mice were all reduced after salubrinal treatment. It suggested that salubrinal attenuated RNV in mRMECs and OIR mice by inhibiting CHOP-HIF1α-VEGF pathways and could be a potential therapeutic target for hypoxia-induced retinal microangiopathy.

Highlights

Retinal neovascularization (RNV) related diseases, such as diabetic retinopathy (DR) and retinopathy of prematurity (ROP), are the most serious blindness-cause diseases in the world [1, 2]
The aim of this study is to identify whether salubrinal could attenuate RNV by inhibiting CCAAT/enhancer-binding protein (C/ EBP) homologous protein (CHOP)- hypoxia inducible factors 1α (HIF1α) -vascular endothelial growth factor (VEGF) pathways in both mouse retinal microvascular endothelial cells and oxygen-induced retinopathy (OIR) mouse model
Salubrinal or CHOP-siRNA treatment significantly reduced HIF1α protein expression and elevated HIF1αOH protein expression (Figure 3). These results suggested that HIF1α protein was unstable and to be degraded after salubrinal down-regulating the CHOP expression in hypoxia-induced mouse retinal microvascular endothelial cells (mRMECs)

Summary

Introduction

Retinal neovascularization (RNV) related diseases, such as diabetic retinopathy (DR) and retinopathy of prematurity (ROP), are the most serious blindness-cause diseases in the world [1, 2]. Anti-vascular endothelial growth factor (VEGF) drugs injection is the most effective therapy for RNV at present. Infection risk and economic burdens restricted the clinical applications of anti-VEGF injection [3]. The hypoxia-inducible factor (HIF) 1 response was activated to avoid neovascularization. The HIF1 transcription factors are comprised of two subunit, α and β. HIF1α subunit is rapidly degraded after being hydroxylated by prolyl hydroxylase (PHD) 2. When suffering from hypoxia, the HIF1α subunit is stabilized, allowing it to dimerize with HIF1β, to form an active transcription factor. VEGF is a www.impactjournals.com/oncotarget well-known target of HIF1α and is one of the most potent pro-angiogenic factors required for neovascularization. Inhibiting the activation of HIF1α-VEGF pathways is an ideal target to attenuate neovascularization

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